1. Field of the Invention
The present invention relates to a process for the production of composite components with a stable adhesive bond, these comprising a structure-imparting support of a thermoplastic and at least one polyurethane layer in direct contact with this support.
2. Description of Related Art
The present invention moreover relates to the use of specific polycarbonate compositions of high melt flowability and toughness in a 2-component injection moulding or 2-component reactive injection moulding process [2C-(R)IM] for the production of a two- or multicomponent part which is distinguished by good adhesive bonding of the PU coating(s) to the support material.
The present invention also provides composite components with a high toughness and stable adhesive bond, these comprising a structure-imparting support of a thermoplastic and at least one polyurethane layer in direct contact with this support, and the use thereof.
DE 196 50 854 C1 discloses a process for the production of a multilayered part of plastic in which an injection moulded part of plastic is coated with at least one layer of a 2-component thermoset, preferably polyurethane. In this process, the part of plastic and the layer of 2-component thermoset are injection moulded successively in a synchronous cycle in the same mould. No indications are given in DE 196 50 854 C1 of the influence of the nature of the support material and of the process parameters on the adhesion between the carrier material and the layer of the composite component joined to this.
U.S. Pat. No. 6,558,599 B1 describes a process for the production of a lacquered part from a formed thermoplastic material. The process comprises the steps
a) injection moulding of the thermoplastic material in a first cavity of a mould for forming the part,
b) opening of the mould for cooling at least the surface of the part, as a result of which shrinkage of the part occurs, and
c) injection of a lacquer into a second cavity of the mould with the part, the second cavity having the same dimensions as the first cavity.
Lacquers which are mentioned as possible in this application are also those based on polyurethane.
However, in U.S. Pat. No. 6,558,599 B1 neither is the support material specified in more detail, nor is an influence of the support material composition on the adhesion properties of the composite component indicated.
WO 2006/072366 A1 describes a process for forming and coating a substrate in a mould with at least two cavities. The process comprises the steps:
a) forming of a substrate in a first cavity of the mould,
b) introduction of the substrate produced in the preceding step into a second cavity of the mould and
c) coating of the substrate in the second cavity with a lacquer, the coating being carried out under increased pressure.
Polyurethane lacquers and PC+ABS substrates (polycarbonate+acrylonitrile/butadiene/styrene substrates) are mentioned by way of example and are preferred. This application says nothing about the influence of the composition of the support and polyurethane material and of possible temperature influences during forming on the adhesive bond.
DE 10 2006 048 252 B3 discloses a process for the production of a composite component, in particular comprising an injection moulded part and a polyurethane element, with the steps
a) production of a support component,
b) introduction or transfer of the support component into an opened cavity of a mould,
c) closing of the mould to a predetermined position, an enlarged cavity with a first size being created,
d) generation of a reduced pressure in the enlarged cavity of the first size,
e) filling of the enlarged cavity with a flooding material and
f) carrying out an embossing step at the same time as the filling and/or after the filling with the flooding material, the cavity being at least slightly reduced in size.
A process as in the present invention in combination with specific compositions for the production of the composite components which have an increased adhesion is not disclosed in DE 10 2006 048 252 B3.
DE 10 2006 033 059 A1 discloses a process for the production of interior parts of plastic. In this, the support is formed in a first mould in a first step, the first mould then being replaced at least in part by a second mould, and the top layer then being formed on the support in a second step. In this process, a hard component, e.g. PA+ABS blends (polyamide+acrylonitrile/butadiene/styrene) or PC+ABS blends (polycarbonate+acrylonitrile/butadiene/styrene), is employed as the support material, and a soft component, preferably polyurethane foam, is employed as the top layer. No indications of the influence of the process parameters and of the composition of the support and polyurethane materials on the bonding properties of the components produced in this way are given in the application. Rather, in DE 10 206 033 059 A1 improvement of the adhesion by primers or laser, corona or plasma treatment is proposed.